A mark visible within the paper when held up to the light. The watermark is made by sewing into the screen of the paper mould a wire impression of the desired mark. When the pulp is placed onto the surface of the screen, these raised wires leave an impression in the pulp such that the area above the wire design is thinner and more translucent, capturing the design of the watermark in the final sheet. Study of a sheet’s watermark can provide useful information about the paper’s date and place of manufacture.